Who knows why this happens â€" or better yet why it is allowed to happen. However, you have a couple of options.

Check to see that there is nothing in the surface and/or subsurface in the area of your bad cells that would cause a problem â€" spikes, overlaps, etc. â€" if there is, fix it. You can then remesh as usual.

Manual cell fixing â€" delete the bad cells, surrounding cells if needed, and click in some new cells by hand. Or you can just delete the bad cell and run the model with a cubic like obstruction. Make sure to check that the remaining CpMatches are valid.